**4.1 Malaria**

Malaria remains one of the deadliest vector-borne disease. Repeated exposure of the malaria vectors to insecticides over several decades has resulted in resistance to many of them. The insecticide resistance in vectors of malaria was first reported in 1950s for DDT [3]. Till date, the vectors of malaria are known to have developed resistance to the four major insecticide classes, *viz.,* pyrethroids, organochlorines, carbamates and organophosphate. Sub-Saharan Africa contributes to 90% and Southeast Asia contributes 7% of the malaria cases reported worldwide, whereas in the Latin Americas, malaria cases have significantly declined, the major contribution of cases now being from the Amazon region [16]. From Africa, all the four major species of *Anopheles,* which are the vector for malaria, have developed resistance to pyrethroids, except in the south-western Africa. In Southeast Asia, resistance to PY has been reported for *An. minimus*, *An. vagus* and *An. sinensis* in China, Thailand and Vietnam [17]. In India, *An. stephensi*, the prime urban vector and *An. culicifacies*, the rural vector of malaria, have developed resistance to PY, DDT and OP in the states of Goa, Tamil Nadu, Orrisa and Chhattisgarh, whereas only one population in western Columbia in the Amazon region has developed resistance to only PY and DDT and not OPs [18]. The resistance to DDT has also been reported in Thailand and Vietnam [19], and in India, the resistance has been reported from Gujarat and Rajasthan [20]. The major vector of malaria in Orrisa, *An. fluviatlis* (S form), and in the Amazon region, *An. darlingi,* are reported to be susceptible to the all classes of insecticides [21]. In addition, the resistance to bendiocarb, a CA which is commonly used in IRS, has also been reported across Africa. The resistance to OP has been limited to only west and east Africa. Multiple resistance to insecticides has been reported from different parts of all these regions [22].
